long count() returns the count of elements in the stream. This is a special case of a reduction (A reduction operation takes a sequence of input elements and combines them into a single summary result by repeated application of a combining operation). This is a terminal operation i.e, it may traverse the stream to produce a result or a side-effect. After the terminal operation is performed, the stream pipeline is considered consumed, and can no longer be used.
Syntax :
long count()
Note : The return value of count operation is the count of elements in the stream.
Example 1 : Counting number of elements in array.
// Java code for Stream.count()// to count the elements in the stream.import java.util.*; class GFG { // Driver code public static void main(String[] args) { // creating a list of Integers List<Integer> list = Arrays.asList(0, 2, 4, 6, 8, 10, 12); // Using count() to count the number // of elements in the stream and // storing the result in a variable. long total = list.stream().count(); // Displaying the number of elements System.out.println(total); }} |
Output :
7
Example 2 : Count number of distinct elements in a list.
// Java code for Stream.count()// to count the number of distinct// elements in the stream.import java.util.*; class GFG { // Driver code public static void main(String[] args) { // creating a list of Strings List<String> list = Arrays.asList("GFG", "Geeks", "for", "Geeks", "Lazyroar", "GFG"); // Using count() to count the number // of distinct elements in the stream and // storing the result in a variable. long total = list.stream().distinct().count(); // Displaying the number of elements System.out.println(total); }} |
Output :
4
